JPS6353277A - Heat resistant surface treating agent for copper or copper alloy - Google Patents

Abstract

PURPOSE:To prevent the tarnish of the surface of copper at high temp. and the deterioration of the corrosion resistance and solderability by treating the surface of the copper with a soln. contg. an amino acid, an ester thereof, an alkali metal, ammonium or amine salt thereof or further contg. specified carboxybenzotriazole. CONSTITUTION:The surface of copper cleaned by degreasing, pickling or other method tarnishes readily at >=100 deg.C and loses the original color tone and luster. In order to prevent the tarnish, the surface of the copper is treated with a treating soln. prepd. by dissolving an amino acid, 1-6C ester thereof, an alkali metal or amine salt thereof in methanol, ethanol, other alcohol or pure water. The treating soln. may further contain carboxybenzotriazole represented by formula I (where R1 is H or 1-12C alkyl), an ester or soluble salt thereof. The tarnish of the surface of the copper at high temp. is prevented and copper maintaining a significant corrosion preventing effect and superior heat resistance characteristics such as solderability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface treatment agent for copper and copper alloys that has excellent heat resistance and is particularly effective at high temperatures.

Copper-based metals, especially clean metal surfaces that have undergone surface treatments such as degreasing and pickling, are extremely susceptible to discoloration, and especially at high temperatures of 100°C or higher, the original color and luster of copper and copper alloys can be completely lost within a few minutes. The surface turns red due to the formation of copper oxide.

Furthermore, it is undesirable because it tends to cause carbonized stain, which significantly deteriorates the properties of copper. Until now, the actual situation has been to avoid discoloration of copper-based metals by using methods such as silver plating or nickel plating as processing methods for this purpose.

As an alternative conventional agent for preventing discoloration of metals including copper and copper alloys at room temperature, for example, benzotriazole and methylbenzotriazole.

benzotriazoles such as hydroxybenzotriazole, dodecylbenzotriazole, etc.;

Alkylimidazoles such as 2-octylimidazole, 2-undecylimidazole, and 2-heptadecyl imidazole are most widely used industrially. Benzotriazoles are recommended because they have excellent anticorrosive properties at relatively low temperatures, from room temperature to below 100°C, but these alone are insufficient as surface treatment agents that have durability at high temperatures. Ta. In addition, alkylimidazoles also have excellent characteristics at room temperature, but 8
At 0°C, there were disadvantages such as discoloration within a few minutes, making it difficult to solder and causing spots.

In view of the above facts, the present inventor has conducted various studies on surface treatment agents that are particularly durable at high temperatures, such as 100°C or higher, have strong discoloration prevention ability, and are also solderable. As a result of repeated treatment, discoloration occurs at high temperatures when copper-based metals are treated by dissolving amino acids, their esters, or alkali metal salts or amine salts of amino acids in alcohols, such as methanol, ethanol, isopropyl alcohol, or pure water. The present invention has been completed based on the discovery that the present invention is a surface treatment agent that prevents heat-resistant soldering and has excellent durability.

The purpose of the present invention is to combine amino acids or amino acids with 1 to 1 carbon atoms.
Provided is a heat-resistant copper and copper-based metal surface treatment agent containing as active ingredients one or more of esters of No. 6 and their alkali metal salts and amine salts, and carboxybenzotriazole and one of its esters or soluble salts. The discoloration inhibitor according to the present invention has the ability to prevent discoloration for a long time at high temperatures, and is characterized in that it can be soldered in that state after heat relieving.

Traditionally, in the manufacturing process of electronic components such as lead frames, curing of resin, bonding process of copper and resin,
Alternatively, during the soldering process, the copper and copper-based metals are exposed to high temperatures of 150°C to 250°C for 48 hours, causing discoloration.Currently, methods such as plating are used to avoid discoloration. It is. The plating process is complicated and is the biggest cause of cost increases, so there was a strong desire from various quarters to develop a chemical that could prevent discoloration of copper and copper-based metals without plating, and that could be soldered as is. The surface treatment agent according to the present invention is an excellent agent capable of preventing discoloration over a wide range of temperatures from room temperature to high temperatures of 250°C or higher, and has great industrial significance.

The reason why the amino acid and its ester according to the present invention have excellent heat resistance and good sustainability can be inferred as follows. Needless to say, amino acids share a carboxyl group and an amino group in one molecule, so they have the property of forming complex salts with various heavy metals. Chemical conversion coatings of copper and copper-based metals and amino acid copper complex salts are stable compounds with high melting points, so they form excellent coatings that have both heat resistance and durability by completely blocking the outside air and the metal. it is conceivable that.

Amino acids that can be used in the present invention include neutral amino acids, basic amino acids, acidic amino acids, sulfur-containing amino acids, aromatic amino acids, and heterocyclic amino acids that can react with copper and copper-based metals to form complex compounds. is included.

Specific examples of preferred amino acids include glycine, alanine, valine, leucine, isoleucine, leucine, lysine, tyrosine, cystine, threonine, serine, arginine, glutamine, glutamic acid, aspartic acid, cysteine, methionine, and phenylalanine.

histidine, oxyproline, hydroxyprotein,
Alcohols that can be used in the synthesis of amino acid esters must have a carbon number of 8 or less;
The above-mentioned alcohols do not provide a sufficient ability to prevent discoloration.The objective of the present invention can be achieved even if the hydrocarbon group of the alcohol is saturated or unsaturated. Specific examples of alcohols include methyl alcohol, ethyl alcohol, propyl alcohol, benzyl alcohol, amyl alcohol, and octyl alcohol. The amino acid ester of the present invention can be synthesized by a known method. For example, in the Fuscher method, an ester compound can be obtained relatively easily by carrying out a heating reaction in the presence of an alcohol through a catalyst of dry hydrogen chloride gas. Alcohol is 1g! Alternatively, two or more types of esters may be mixed in advance and reacted, or two or more types of esters may be synthesized and then mixed.

The surface treatment agent of the present invention can of course be used only with the above-mentioned amino acid ester, but may also contain amino acids.
In addition, the amino acid may be used alone, and in order to achieve a complete effect, carboxybenzotriazole or an ester of carboxybenzotriazole, such as ester or soluble salt of methyl, ethyl, isopropyl, butyl, hexyl, octyl, dodecyl, etc., may be used in combination. As a result, it has excellent discoloration prevention ability from room temperature to temperatures of 250° C. or higher, and exhibits a synergistic effect at high temperatures.

The biggest feature of the surface treatment agent of the present invention is that the temperature is 150°C to 300°C.
The aim is to create a chemical conversion film with excellent heat resistance that does not discolor the copper surface even at such high temperatures, and to provide a durable discoloration prevention ability. Therefore, the surface treatment agent of the present invention can be effectively used as a surface treatment agent for corrosion prevention of lead frames, copper foil, electric wires, etc., which have been frequently used in recent years. In this case, the anticorrosive agent according to the present invention contains 0.01 to 2.0 parts by weight of carboxybenzotriazole or its ester per 1 part by weight of the amino acid or its ester, and the sum thereof is 0.03 to 5.0%. It is most effective to treat by dissolving it in a solvent such as alcohol or water and immersing it or spraying it.
A durable and heat-resistant chemical conversion film that hardly discolors even after being left for a long time can be obtained.

Next, the present invention will be specifically explained using reference examples and examples.

Reference Example 1.4 Synthesis of Threonine Ethyl Ester A round bottom flask is charged with 0.1 mole of threonine and 100% of ethanol, and dry hydrogen chloride gas is passed through the flask to saturate the flask, gradually generating heat and threonine gradually dissolving in the ethanol solvent.

After boiling and refluxing in this state for 2 hours, the solvent is removed under reduced pressure at a temperature of 60° C. or lower to obtain oily threonine ethyl ester hydrochloride.

Reference Example 2.7 Synthesis of Carpoxybenzotriazole Methyl Ester "0.1 mol of carboxybenzotriazole and 100 alt of methanol were boiled and kept at reflux temperature, and 0.2 mol of thionyl chloride was added dropwise over 2 hours and 30 minutes to complete the reaction. .

After passing the crystals through the mouth, washing with water, and drying at 160'C, the temperature is 13.5.
g of methyl ester was obtained. The yield was 81%.

Example 1 Lead frame degreased with Triclean (thickness 0.5I width 3
0x200m-) was immersed in 6N hydrochloric acid for 60 seconds, washed with water, washed with methanol, and dried.The lead frame was used as a test piece and was immersed for 3 seconds in a solution containing the surface treatment agent of the present invention shown in the table. , dried. A test piece subjected to such surface treatment was held at 200±3° C. for 24 hours to conduct a discoloration test. The results obtained are shown in Table I. The values in Table I are:

According to JIS K 2513 copper plate corrosion classification table.

Example 2゜Example 1. The test piece obtained by JISC2519
A soldering test was conducted using this flux. The results are shown in Table ■.

As a result of the above, it was found that the product of the present invention has an excellent anticorrosion effect at high temperatures and has excellent soldering properties even after being heat resistant.

Claims (1)

[Scope of Claims] [1] The surface of copper or copper alloy is subjected to contact treatment with one or more of amino acids, their esters, or alkali metal salts, ammonia, or amine salts of amino acids as active ingredients, and the surface of these metals is treated with A heat-resistant surface treatment agent for copper and copper alloys by forming a chemical conversion film on the surface. [2] One or more amino acids or their esters or alkali metal salts, ammonia or amine salts of amino acids and general formulas; ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ [In the formula, R_2 is a hydrogen atom or C_1~ C_2_ represents an alkyl group. ] The heat-resistant surface treatment agent for copper and copper alloys according to claim 1, which contains carboxybenzotriazole or its ester or soluble salt as an active ingredient.